Traffic ‐and Industry‐Related Air Pollution Exposure Assessment in an Asian Megacity          下载免费PDF全文

Muhammad Usman Alvi  Farrukh Chishtie  Imran Shahid  Tariq Mahmud  Riaz Hussain 《洁净——土壤、空气、水》2018,46(1)

Like other Asian countries, Pakistan is facing the issue of air pollution due to rapid urbanization, enormous transportation increases, and other related human activities. Moreover, continuously increasing emission sources have not only raised pollutant concentrations but also their types, thus damaging both human health and the environment. Faisalabad is the third largest megacity of Pakistan and its state of air quality is getting worse due to factors such as industrialization, high traffic volumes, and extensive fossil‐fuel‐burning activities. This review article aims to highlight the present status of air pollution in this city with special reference to particulate matter, elemental profiles, gaseous pollutants, organic–inorganic particulate contents as well as their sources. The concentration levels of these entities were also compared with other national and international cities, and related environmental standards. It is found that current levels of these pollutants are beyond safety limits as specified by various environment protection agencies and organizations. Several weak aspects and gaps are also identified along with suggestions for improvements of the present situation and directions for future research.  相似文献   

Water percolation in a thick unsaturated loess layer considering the ground‐atmosphere interaction     

Xiaokun Hou  Tonglu Li  Sai K. Vanapalli  Yu Xi 《水文研究》2019,33(5):794-802

The key objective of this paper is to advance our present understanding of how surface water infiltrates in thick unsaturated loess, which is found in arid and semiarid regions of the world, considering the ground‐atmosphere interaction. In situ data for a period of 1 year in thick loess layer at a site in the Loess Plateau of China that has groundwater table at 97.5 m depth were collected for achieving this objective. Climate factors, mainly rainfall and actual evaporation, were measured. In addition, variations of soil temperature and water content at different depths in the unsaturated zone were also measured. The data were used to interpret the water percolation characteristics by dividing the thick unsaturated zone into three zones; namely, (i) surface zone, which constitutes the top 1.0 m, (ii) unsteady zone, which is from 1.0 to 7.0 m, and (iii) steady zone, which is below 7.0 m. In the surface zone, soil temperature and water content are sensitive to climate factors. There is a variation of water content associated with the cumulative influence of infiltration and evaporation in the precipitation and nonprecipitation periods, respectively. In the unsteady zone, the water content is relatively constant; however, temperature varies in different seasons. Water percolation in this zone is both in liquid and vapour phases. In the steady zone, both soil temperature and water content are constant during the entire investigation period. The percolation velocity in this zone is approximately 1.23 × 10^?8 m/s or 0.39 m/year, which suggests that it will take approximately 230.8 years for surface water to pass through the thick unsaturated zone and recharge the groundwater.  相似文献   

Moving beyond run‐off calibration—Multivariable optimization of a surface–subsurface–atmosphere model          下载免费PDF全文

Simon Stisen  Julian Koch  Torben O. Sonnenborg  Jens Christian Refsgaard  Simone Bircher  Rasmus Ringgaard  Karsten H. Jensen 《水文研究》2018,32(17):2654-2668

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Study About Ocean Eddy Effect on Strong Convection in Local Atmosphere over the Kuroshio Extension Region     

Qinyu Liu  Suping Zhang  Yinglai Jia 《地球科学进展》2020,35(5):441-451

The Kuroshio Extension （KE） is the key area where the water heats the atmosphere in the northwestern Pacific Ocean in winter. Previous studies show that the active eddies in the KE area can affect sea surface temperature and thus sea surface winds. The present study reviewed the progress about the influences of the eddies on local atmosphere in recent years. Analysis and comparison were made especially for the achievements from shipboard sounding data, satellite observations and numerical experiments. Based on the geostrophic adaptation theory involved in atmospheric anomalies induced by the eddies, the following new scientific deductions were suggested: Air pressure adjustment mechanism dominated in the atmospheric response to eddies under the conditions of weaker wind speed over the eddies. The influence of eddies was often limited in the atmospheric boundary layer. On the other hand, vertical mixing mechanism played a major role in the response of the atmosphere to warm (cold) eddies when air moved faster over the eddies. Surface wind speed increased (decreased) over the warm (cold) water. Significant wind convergence took place downwind the warm water, and large amount of water vapor was transported also downwind from the warm water surface. The positive feedback between water vapor condensation and rising air forced by the surface convergence provided necessary conditions for the development of strong convection in atmosphere. These deductions will be conducive to further depicting the impact of oceanic eddies on the atmosphere quantitatively.  相似文献   

海洋表面大气下行辐射遥感估算     

王春磊  唐伯惠 《海洋通报》2018,(2):219-224

在海-气相互作用研究中,大气下行辐射的准确估算具有重要意义。在气象站点分布密集的地区,大气下行辐射可通过常规的仪器测量获取。但海洋表面布点成本高,维护比较困难,严重影响我们对海区辐射特征的认识和了解。遥感可提供良好的时空连续性和多层次数据,是研究大气下行辐射的有效手段。本文模拟了不同大气条件下海表的长波下行辐射,考虑到大气下行辐射不仅与所在层的大气有关,还受临近大气层的影响,我们通过增加大气水汽含量重新参数化大气比辐射率,改进Brutsaert模型,建立基于MODIS数据遥感估算海洋表面大气下行辐射的模型,并利用"中国近海海洋综合调查与评价"项目中黄海区观测的海-气通量观测资料对所提出的模型进行检验。结果表明,本文所改进的参数化模型在模拟数据中的均方误差(RMSE)为11.2 W/m~2;在实际数据验证中,RMSE为20.9 W/m~2;模型的精度基本达到了海-气作用研究中对瞬时大气下行辐射的精度要求。  相似文献   

等温大气压高方程在气压剖面高度计算中的应用   总被引：2，自引：0，他引：2  

董涛  李永军 《海洋技术学报》2011,30(1):88-90,94

气象探测仪器获取空中气象数据时,需要确定气象数据对应的气压高度,以形成剖面测量数据.将等温大气压高方程应用于实际的气压剖面高度计算中,确定计算的边界条件并进行误差估算,并通过实际算例,验证了理论计算的有效性.  相似文献   

二维大气模型在海上电波传播中的应用     

邵轩  楚晓亮  王剑 《中国海洋大学学报(自然科学版)》2011,41(9):109-113

电磁波在海上波导环境下传播特性的研究对提升舰载雷达探测性能有重大意义。通用的波导环境折射率模型是基于莫宁相似理论的5参数经验模型,其缺陷在于将折射率的水平结构看作是均匀的。本文运用的二维波导环境10参数模型克服了先前模型的缺陷,对实际波导环境有更近似的描述。最后运用基于离散傅里叶正弦变换的抛物方程方法具体分析了波导环境中折射率水平方向的变化对电波传播产生的影响,结果表明折射率水平变化会改变电磁波的空间场强分布,二维折射率模型更具实用价值。  相似文献   

植被对季节内振荡影响的数值模拟          下载免费PDF全文

HAN Ying  XU Zhong-Feng 《大气和海洋科学快报》2011,4(1):1-6

The influences of vegetation on intraseasonal oscillation (ISO) were examined using the Community Atmosphere Model version 3 (CAM3).Two 15-year numerical experiments were completed:the first was performed with a realistic vegetation distribution (VEG run),and the second was identical to the VEG run except without land vegetation (NOVEG run).Generally speaking,CAM3 was able to reproduce the spatial distribution of the ISO,but the ISO intensity in the simulation was much weaker than that observed in nature:the ISO has a relatively much stronger signal.A comparison of the VEG run with the NOVEG run revealed that the presence of vegetation usually produces a weak ISO.The vegetation effects on ISO intensity were significant over West Africa and South Asia,especially in the summer half-year.Vegetation also plays an important role in modulating ISO propagation.The eastward propagation of the ISO in the VEG run was clearer than that in the NOVEG run over the West African and Maritime Continent regions.The northward propagation of the ISO in the VEG run was more consistent with observation than that in the NOVEG run.  相似文献   

中层大气重力波的全球分布特征   总被引：6，自引：3，他引：3       下载免费PDF全文

张云  熊建刚  万卫星 《地球物理学报》2011,54(7):1711-1717

从2002年1月到2009年12月的SABER温度剖面数据提取了可以反映重力波活动的垂直尺度2～10 km的中尺度温度扰动,分析了全球中层大气重力波的分布.重力波扰动在夏季和冬季明显强于春季和秋季,而冬季与夏季相比,在70 km以下的高度夏季弱于冬季,在70 km以上夏季比冬季要强.从全球重力波分布来看,较大值分布在冬...  相似文献   

重力计算中的气压改正分析   总被引：2，自引：2，他引：0  

张宏伟  刘子旭  肖凡 《北京测绘》2011,(4):12-15

首先介绍了气压及其单位的变换,同时列举出重力计算中的许厚泽气压改正模型的几种不同表现形式,通过我国各地气压值共2046个数据统计绘制出气压改正值等相关等值线图,使其更加形象直观,便于检验计算.  相似文献